1. Technical Field
The present invention relates to a magnesium-based alloy powder, and a magnesium-based alloy molded article.
2. Related Art
Magnesium represents an abundant natural resource with its Clarke number (the proportion of elements present in the vicinity of the Earth's crust) at least 100-fold higher than that of nickel or copper. The specific gravity of magnesium is about ⅔ of that of aluminum, and about ¼ of that of iron. Structures produced from magnesium can thus be made much lighter than structures produced from these other metals. Over these backgrounds, magnesium alloy components have been used in a variety of products such as automobiles, aircraft, cell phones, and laptop personal computers.
Magnesium also has other desirable properties, including electromagnetic wave shielding performance, vibration damping capacity, ease of cutting, and biological safety.
Magnesium structure production employs various methods, including, for example, casting such as gravity casting, and die-casting, plasticization such as billet hot extrusion, cold extrusion, press-rolling, and forging, and powder metallurgy methods such as molding by hot pressing or hot extrusion of powder. The powder metallurgy methods can suppress local composition fluctuations, and can produce more homogeneous structures.
A problem of magnesium, however, is that it is highly flammable in the atmosphere. Magnesium powder, in particular, has the danger of causing the phenomenon called dust explosion by floating in air. This makes it practically impossible to simply replace common metallic materials and metal powders with magnesium, and prevented use of magnesium as structural material.
In view of these problems, magnesium has been studied for its flame retardance, and it has been found that adding calcium imparts flame retardance to magnesium. For example, JP-A-2010-82693 discloses a Mg alloy extruded material containing 4 to 8 mass % of calcium. Such flame-retardant magnesium has a firing temperature of 200° C. or higher than common magnesium, and improves not only the flame retardance of the structure itself, but the safety of structure production. The flame-retardant magnesium is thus expected to widen the use of magnesium structures.
The problem of the flame-retardant magnesium, however, is the poor mechanical strength. This has created the need to develop a material that can be used to produce a flame-retardant magnesium-based metal molded article of improved mechanical properties.